Quantitative characters vary in a population along a continuum. How do such characters differ from the characters investigated b
y Mendel in his experiments on peas? A. Environment and genes affect quantitative characters, whereas only genes determined the pea characters studied by Mendel.
B. The nature of inheritance of quantitative characters is poorly understood, and Mendel understood the nature of inheritance for the characters he studied in his peas.
C. Quantitative characters are due to polygenic inheritance, the additive effects of two or more genes on a single phenotypic character.
D. A single gene affected all but one of the pea characters studied by Mendel.
C. Quantitative characters are due to polygenic inheritance, the additive effects of two or more genes on a single phenotypic character.
Explanation:
Mendel studied the discrete traits that were present in observable contrasting phenotypes. Tall or dwarf stem, purple or white flowers, round or wrinkled pods are some of the examples of discrete traits. Each of these traits is mostly regulated by two alleles of a gene.
On the other hand, a polygenic trait is the one that is regulated by more than one gene. Quantitative traits are polygenic traits. The alleles of all the genes that regulate a quantitative trait have an additive effect on the phenotype. For example, human skin color is a quantitative trait and shows continuous variation. There is a range of human skin color regulated by the sum total of effects of all the alleles of the regulatory genes present in an individual.
An individual with "aabbcc" genotype would have very light skin color while an individual with "AABBCC" genotype would have a very dark skin color. The skin color of the intermediate genotype would be in between these two extreme phenotypes.
Gene expression is the process by which the information encoded in a gene is used to direct the assembly of a protein molecule. The cell reads the sequence of the gene in groups of three bases.
